Snap acting mechanism



P. V. TERRY SNAP ACTING MECHANISM 2 Shets-Sheet 1 Filed Dec. 28, 1954 lnvenior:

' Paul V. Terry His Arrornex p 1957 P. v. TERRY 2,788,410

SNAP ACTING MECHANISM Filed Dec. 28. 1954 2 Sheets$heet 2 Fig.5

SNAP ACTING MECHANISM Paul V. Terry, Eliot, Maine, assignor to General Electric Company, a corporation of New York Application December 28, 1954, Serial No. 478,073 9 Claims. (Cl. 200-67) This invention pertains to a snap acting mechanism and particularly to a snap acting mechanism as it is applied in an electric switch used for alternately opening and closing electric circuits and has for its object the provision of a simple, inexpensive, and durable quick acting controller.

The present invention provides for snap action in a mechanism designed to convert rotative movement to oscillatory movement. A preferred embodiment incor' porates a rotatable element, an interconnecting means in the form of a resilient member, and a pivoted lever. As one end of the resilient member moves about an axis of rotation, the other end urges the lever to move about its pivot. In its movement, the end of the lever describes a path through space. A restraining element which is coordinated to move with the rotative element is positioned with respect to the moving parts to move into this path to engage the lever for a discreet period of time. During such period of time, the oscillation of the lever is interrupted. One end of the resilient means, the restraining means, and the rotative element continue to move, however. The continued movement results in an expansion of the resilient member whereby energy is stored therein. During the continued movement the restraining element is being removed from the path of the levers movement. When the removal is complete, the lever is free to move and does so with a snap action under the impetus supplied by the energized resilient element. A complete cycle of oscillation occurs once for each revolution of the rotative element. As applied to a switch the invention incorporates a lever which is adapted to operate contact elements in a snap acting manner.

The features of this invention which are believed to be novel are set forth with particularity in the appended claims. as to organization and operation as well as to further objects and advantages by reference to the following description taken in connection with the accompanying drawings in which:

Fig. 1 is a switch, in perspective, constructed in accordance with the invention.

Figs. 2-5 are front views of the snap acting mechanism depicting various stages of operation during a complete cycle.

Like numerals designate like parts in the various figures.

Referring to Fig. l, numeral 1 designates a support member upon which the snap action mechanism and switch elements are mounted in operative relation. Insulating block 2 is affixed to support member 1 by screw 3. Contact members 4, 5, and 6 are mounted on block 2 insulated from each other in any well known manner. Each of the contact members may be provided with raised portions such as shown at 7. Electric conductors 8, 9, and 10 are connected to terminals of the contact members in any well known manner. A contact actuator The invention itself may be better understood in the form of a crank lever 24 is mounted for pivotal oscillatory motion on post 25 which is fixedly mounted on support member 1. A rotatable element 20 depicted as a gear wheel is mounted on shaft 21 which is mounted on support 1 by any suitable bearing means (not shown). A driving pinion 19 is positioned to engage gear wheel 20 to impart motion thereto. It is to be understood that rotatable element 20 may take any form and that the prescribed motion may be imparted directly or indirectly thereto by any of a variety of well known means. Interconnecting means which may be a resilient member in the form of a coil spring 22 is connected to rotative element 20 by means of anchor peg 23 and to crank lever 24. Both connections may be made in any well known fashion which assures firm connections. A restraining means 27 is depicted in a preferred embodiment as an extension of shaft 21 which has been cut away in part to provide an arcuate bearing surface 28 which is operative to engage follower 26 on crank lever 24. It is to be understood that the arcuate surface 28 need not be an integral part of shaft 21 but may be any means attached to the rotative element 20 so as to be radially disposed from the axis of rotation. Where the arcuate surface 28 is an integral part of shaft 21 it is adjacent to a cutaway portion which allows passage of follower 26 therethrough. The cutaway portion is provided by cutting along a line describing plane 29 so that plane 29 is generally parallel to the axis of shaft 21. The cutaway portion in its preferred form is made so as to allow the end of lever 24 to pass through the axis of shaft 21 in order that the force causing snap action is largely radial without substantial vertical components; however, the cutaway may be made of any size as a convenient means, if desired, of controlling the amount of arcuate bearing surface 28 available as a restraining means. A second end of crank lever 24 is adapted to engage a switching element such as contact element 5. Such an adaptation may be in the nature of a cutout 30 providing finger elements 31 and 32. The lever 24 is positioned with respect to the switching elements so that the end of contact element 5 extends into cutout 30 for operation under the force applied through fingers 31 and 32.

Reference to Figs. 2-5 is made for purposes of understanding operative performance of the snap acting mechanism. To facilitate description a vertical line A-A' and a horizontal line BB have been superimposed on the Figs. 2-5 to intersect at the axis of rotation of rotative element 20 so as to provide standard quadrants. Fig. 5 shows peg 23 on line B-B' between quadrants III and IV. Lever 24 is in one limiting position and spring 22 is in a contracted state. As element 20 rotates clockwise, peg 23 moves into quadrant I (Fig. 2), at the same time restraining means 27 has been rotated to bring surface 28 into position to engage follower 26 of lever 24. Lever 24 has moved slightly from the limiting position shown in Fig. 5. In its switch application, the parts may be assembled so that this slight movement does not separate the contacts. Separate stops may be provided to reduce the amount of travel of the lever beyond the axis of rotation or-the stopping function may be fulfilled by the switch contacts. As peg 23 continues to be rotated clockwise follower 26 is brought into engagement with surface 28 which continues to rotate with peg 23 and element 20. The lever 24 is thus restrained in its movement for a discreet period of time depending on the speed of rotation and the length of surface 28. During the restraint period, spring 22 is extended to become stored with energy. As peg 23 approaches line B-B between quadrants I and 11, surface 28 is removed from contact with follower 26. Lever 24 is then free to move toward peg 23 under impetus supplied by avsasw spring 22. In so moving lever 24 passes through the cutaway portion described previously as the preferred embodiment.

Figs. 3 and 4 describe the initial stage of the remainder of the rotativc cycle. in 3 spring 22 is contrwted, peg Z3 is on the line between quadrants l and ii, and lever 2 is in its other limiting position. Rotation of peg 2,3 to the intermediate position shown in Fig. 4 results in movement of spring 22 to cause lever to move slightly its limiting position whereby follower 26 engages surface Continued rotation results in expansion of spring 22, and subsequent removal of surface 28 from contact with follower 26 so that lever 2d moves with a. snap acting motion.

Although clockwise motion of element is described, countercrockwise motion may be obtained by rearranging the position of restraining means It? to positions diametrically opposite its positions as shown.

Therefore, while a particular embodiment of the subject invention has "con shown and described herein, it is in the nature of description rather than limitation, and it will occur to those skilled in the art that various changes, modifications, and combinations ma be made within the province of the appended claims, and without departing either in spirit or scope from this invention in its broader aspects.

What I claim as new and desire to secure by Letters Fatcnt of the United States is:

l. A snap acting mechanism comprising a rotatable element having an axis of rotation, a pivoted lever adapted to have one end describe a path of movement through said axis of rotation, a resilient energy storing member connected to said rotatable element and said pivoted lever and adapted to move said end of said pivoted lever along said path in a snap acting manner, and means movable conjointly with said rotatable element adapted to be movable into said path to restrain movement of said pivoted lever for a discreet period of time, said restraining means being movable out of said path upon completion of said period of time to permit motion of said end of said lever along said path.

2. A snap acting mechanism comprising a rotatable element having an axis of rotation, a pivoted lever adapted to have one end describe a path of movement through said axis of rotation, a resilient energy storing member connected to said rotatable element and said pivoted lever and adapted to move said end of said pivoted lever along said path in a snap acting manner, and an arcuate bearing surface means movable ccnjointly with said rotatable element radially disposed with respect to said axis of rotation and adapted to move across said path for a discreet period of time to restrain said pivoted lever, said bearing surface means being movable out of said path upon completion of said period of time to permit motion of said end of said lever along said path.

3. A snap acting mechanism comprising a rotatable shaft, a substantially rigid member secured to said shaft for rotation therewith, a pivoted lever adapted to have one end thereof describe a path of movement across the end of said shaft, resilient means connected to said pivoted lever and said rigid member and adapted to move said end of said pivoted lever along said path in a snap acting manner, and an extending arcuate surface bearing means formed in the end of said shaft subtended by a plane parallel to the axis of said shaft, said surface hearing means being movable across said path for a discreet period of time to restrain said pivoted lever and movable out of said path upon completion of said period of time to permit motion of said end of said lever along said path.

4. A snap acting mechanism comprising a rotatable shaft having a cutaway portion in one end of said shaft, an extending arcuate surface adjacent said cutaway portion subtended by a plane parallel to the axis of said shaft, a pivoted lever adapted to selectively bear upon a; said arcuate surface and to move through said cutaway portion, a rigid member mounted on said shaft for rotation therewith, a resilient member connecting said rigid member and said lever and adapted to impart snap action to said lever, said rigid member adapted to rotate said shaft whereby said arcuate surface and said cutaway portion are moved to successively restrain and release said pivoted lever.

5. An electric switch of the double throw type comprising a rotatable element, a pivoted contact actuator operable along a path between two limiting positions relative to said element, resilient means connecting said element and said actuator whereby rotation of said element causes movement of said lever between said positions, and restraining means movable conjointly with said element and adapted to aiternately hold and release said actuator during movement thereof whereby said actuator is moved in a snap acting manner.

6. An electric switch of the double throw type comprising a rotatable element including a shaft, a pivoted contact actuator operable relative to an end of said shaft along a path between two limiting positions, and resilient means connecting said element and said actuator whereby rotation of said shaft causes movement of said actuator between said positions, said shaft having an end adapted to have a restraining means capable of rotative movement into and out of said path to successively hold and release said actuator for operation in a snap acting manner.

7. An electric switch of the double throw type comprising a rotatable element including a shaft having an end formed to present an axially extending bearing surface subtended by a plane parallel to the axis of rotation, a pivoted contact actuator operable between two limiting positions, said actuator having a follower portion thereon movable so as to describe a path in proximity to and across the end of said shaft, and resilient means connecting said element and said follower portion of said actuator whereby rotation of said element causes said follower to move along said path between said limiting positions, said follower portion being alternately restrained and released by movement of said bearing surface across said path to effectuate snap operation of said actuator.

8. An electric switch of the double throw type comprising a rotatable shaft having an axial cutaway portion therein, a gear fixedly mounted on said shaft proximate said cutaway portion, means for driving said gear to rotate said shaft, a pivoted switch actuating lever operable between two limiting positions on opposite sides of said she. t and adapted to have a follower portion for engaging said shaft while in said limiting positions, and a coil spring having one end connected to said gear at a point radially displaced from said shaft along a line extending through said cutaway portion thereof and the other end connected to said lever whereby rotation of said gear causes said coil spring to be extended to cause said follower portion to move through said cutaway portion in a snap acting manner upon alignment of said cutaway portion and said follower.

9. An electric switch of the double throw type comprising a rotatable element including a shaft having an axial cutaway portion therein, a pivoted contact actuator operable between two limiting positions adapted to have follower portion for engaging said shaft upon movement between said limiting positions, and resilient means connecting said rotatable element and said actuator whereby rotation of said shaft causes said actuator to move to said positions, said follower portion of said actuator alternately engaging said shaft and moving through said cutaway portion to thereby cause said actuator to operate in a snap acting manner.

(References on foiiowing page) 1,693,635 Chandler Dec. 4, 1928 1,863,494 Lyons June 14, 1932 1,943,839 Rhodes et a1. Ian. 16, 1934 2,010,026 Lipp Aug. 6, 1935 6 McComb Dec. 10, 1935 Porter Feb. 27, 1940 Bramley May 8, 1951 Gaynor Mar. 2, 1954 FOREiGN PATENTS France June 13, 1927 

